The Clinical Core will provide 4 categories of essential supportive functions: (1) Accession and Coordination of Study Subjects: These activities include contacting subjects, scheduling visits to the University of Minnesota Hospital and Clinics (UMHC) Bob Allison Ataxia Clinic and the other clinical study facilities, both coordinating and funding subject travel for studies, and triaging and arranging the shipment of biological samples. (2) Subject Evaluations: Detailed subject evaluations beyond those obtained in the course of 'routine' clinical care will be performed in order to provide a basis of more precise understanding of the clinical presentation (qualitative and quantitative nature of neurological deficits) and natural history of the ataxias, on the one hand, and the relationships of these two parameters to the type and severity (e.g., number of DNA triplet repeats) of genetic defects, biochemical abnormalities and altered anatomy and pathophysiology (e.g., as revealed by functional neuroimaging), on the other hand. These evaluations will include: standardized clinical neurological assessments, genetic and familial analysis, broad and specialized quantitative neurological assessments and anatomic neuroimaging using MRI. 3. Biological Sample Management: Blood samples will be collected and both white blood cells (for DNA analysis) and sera will be archived for genetic and biochemical studies. Autopsy will also be facilitated and performed for anatomic and molecular correlations. (4) Ataxia Data Unit: A database will be created and maintained for cross-sectional and longitudinal analysis of disease phenotype and natural history, for correlative studies related to Projects 3 and 4, and as a resource for future work which will take advantage of developments in the field.